Numerical Investigation of Active Flow Control of Low-Pressure Turbine Endwall Flow

The endwall flow in a highly loaded linear low-pressure turbine cascade has been numerically investigated for a chord-based Reynolds number of 100,000. Mean flow visualizations reveal a horseshoe vortex at the endwall-leading edge junction. The pressure side leg of the horseshoe vortex develops into...

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Bibliographic Details
Published in:Journal of propulsion and power 2019-09, Vol.35 (5), p.883-895
Main Authors: Romero, S, Gross, A
Format: Article
Language:English
Subjects:
Active control
Blowing pressure
Blowing time
Computational fluid dynamics
Corner flow
Flow control
Fluid flow
Horseshoe vortices
Low pressure
Modal analysis
Pressure loss
Reynolds number
Secondary flow
Suction
Topology
Turbines
Unsteady flow
Vortices
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Summary:The endwall flow in a highly loaded linear low-pressure turbine cascade has been numerically investigated for a chord-based Reynolds number of 100,000. Mean flow visualizations reveal a horseshoe vortex at the endwall-leading edge junction. The pressure side leg of the horseshoe vortex develops into a highly coherent passage vortex. The passage vortex is supported by a strong secondary flow that impinges on the endwall and spreads in the pitchwise direction. A dynamic mode decomposition reveals temporally growing three-dimensional modes that are susceptible to unsteady flow control. Based on the modal analysis and physical understanding of the mean flow topology, several different steady and unsteady flow control strategies were devised for weakening the passage vortex, countering the secondary flow, and reducing the suction side corner flow separation. Steady blowing that directly opposes the secondary flow effectively lowers the total pressure losses but requires large amplitudes, which makes it inefficient. Unsteady forcing is demonstrated to be an efficient way for decreasing the coherence of the passage vortex and for obtaining a moderate reduction of the total pressure losses.
ISSN:1533-3876
0748-4658
1533-3876
DOI:10.2514/1.B37281